1. Field of the Invention:
This invention relates to a signal reproducing apparatus wherein signals recorded on a record bearing medium having many recording tracks formed thereon are reproduced by a reproducing head which is arranged to periodically trace the medium.
2. Description of the Prior Art:
In this specification, apparatuses of the above-stated kind are represented by way of example by a two-head helical scanning type video tape recorder (hereinafter will be called VTR for short). In the VTR of this type, in order to reproduce a still picture without any noise bars (hereinafter will be called noiseless still reproduction), the VTR of the above-stated kind has been arranged to detect the rotation phase of the reproducing head relative to the recording tracks by reproducing control signals (hereinafter referred to as CTL signals) which are recorded in the longitudinal direction of a magnetic tape employed as the record bearing medium and to bring the travel of the tape to a stop by using information on the phase thus detected. Further, slow motion reproduction has been arranged to be carried out by alternately repeating the noiseless still reproduction and normal reproduction. The details of the slow motion reproduction of this type (hereinafter will be called noiseless slow reproduction) are as described below with reference to FIG. 1 of the accompanying drawings:
Referring to FIG. 1, during a period from a point of time t0 to another point t1, the capstan motor which is used for control over tape feeding is controlled to accelerate its rotation. Then, the motor comes to rotate at a constant speed (lower than a normal speed) at the time t1. Following this, one of the CTL signals which have been written in along the edge of the tape in a predetermined positional relation to recording tracks every time one frame portion of a video signal is recorded is detected at a point of time tc. The tape is allowed to travel at the constant speed during the period from the point of time tc to another point t2. Then, the capstan motor is stopped by brake application to have the tape in repose during a next period between points of time t2 and t3 to have the tape under still reproduction. The process of still reproduction is repeated a number of times according to the desired speed of reproduction. Following this, the above-stated operation is repeated to carry out the noiseless slow reproduction. An extent of tape movement between points Q0 and Q3 represent one frame. A tape moving extent Qc before detection of the CTL signal is controlled to be in the middle of the tape moving extent from the point Q0 to the point Q3.
The operating principle of the noiseless slow reproduction by the conventional tracking method using the CTL signal is as described above. As apparent from the above description, the CTL signal serves as a reference signal indispensable for control over the stopping position of still reproduction. The illustration of FIG. 1 includes a magnetic tape 4; recording tracks 5; the CTL signal; and a still reproduction point S.
Meanwhile, as a result of a recent tendency to high density recording, it has been proposed and put into practice to arrange a VTR to perform tracking without recording and reproducing the CTL signal. However, unlike the VTR using the CTL signal, the VTR of this kind has been incapable of readily finding a positional relation between the head and the track and, therefore, hardly usable for slow motion reproduction.